Recently, micropatterned damascene interconnections and contact plugs mainly containing Cu are formed by using CMP (Chemical Mechanical Polishing). However, the CMP process is more expensive than other semiconductor manufacturing steps. Therefore, it is important to reduce the cost of the CMP process.
In particular, a slurry (polishing solution) occupies most of the cost of the CMP process. Reducing the supply amount of the slurry is an example of a method of reducing the cost of the slurry. However, the CMP characteristics deteriorate if the supply amount of the slurry is reduced. That is, the cost reduction and the improvement of the CMP characteristics have a tradeoff relationship.
More specifically, the following problems arise when performing CMP by reducing the slurry supply amount.
When forming, e.g., a micropatterned damascene interconnection by performing CMP on a thin Cu film (e.g., 400 nm), Cu dishing, corrosion, dust, scratch, the Cu residue, and the like increase. That is, the CMP characteristics deteriorate.
Also, when forming, e.g., a contact plug (TSV: Through Silicon Via) by performing CMP on a thick Cu film (e.g., 1 to 3 μm), the polishing time prolongs. That is, even when the supply amount of the slurry is reduced, the use amount of the slurry increases, and the cost increases.
Accordingly, demands have arisen for a method that reduces the cost by efficiently using an expensive slurry, and improves the CMP characteristics.